Well, my Lounge Room PC stopped working, and that was that!

Well, my Lounge Room PC stopped working, and that was that! I think it's the power supply. It spontaneously rebooted twice in the last two months, and on one occasion gave an error message about the power supply. I was going top wait until I got back from New Zealand to replace that - which I still might do. Trouble is that the Lounge Room PC is also my home network server. Oops!

UPDATE:
I flicked switch at the back OFF and then ONE, and pressed the "On button" on the front again, and it booted! However, that switch is part of the power supply, so I think my diagnosis is still correct. Time to backup while I can, and move the stuff on the server to another PC.